Method of forming thin film magnetic recording head with narrow track width performing high density recording at high driving frequency

ABSTRACT

A method of forming a thin film magnetic head, including forming a first magnetic layer, forming a second magnetic layer as a magnetic flux passage in combination with the first magnetic layer, and forming a laminate structure body between the first magnetic layer and the second magnetic layer. The forming of the laminate structure body includes forming a third magnetic layer, a fourth magnetic layer and a non-magnetic conductive layer between the third magnetic layer and the fourth magnetic layer, projecting the laminate structure body more toward an air bearing surface than a projection of the first magnetic layer and the second magnetic layer toward the air bearing surface, and providing the laminate structure body with a width which is smaller than a width of the first magnetic layer and the second magnetic layer.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This is a continuation of U.S. application Ser. No. 09/616,907,filed Jul. 14, 2000, which is a continuation of U.S. application Ser.No. 09/048,985, filed Mar. 27, 1998, now U.S. Pat. No. 6,091,582, thesubject matter of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a novel thin film magnetic head,a recording/reproduction separation type head using the thin filmmagnetic head, and a magnetic recording and reproducing apparatus.

[0003] A thin film magnetic head for a magnetic disk apparatus is formedon a slider held above a disk which rotates at high speed. The magnetichead has a magnet pole layer in the form of a thin film made of aferromagnetic material. On an air bearing surface (ABS), a lowermagnetic pole layer and an upper magnetic pole layer are provided on andunder a gap layer. The upper and lower magnetic pole layers of therecording head are in contact with each other in the rear part of thegap. In order to increase the recording density, it is necessary towrite a large amount of data on the surface of a magnetic disk. For thispurpose, it has been proposed to narrow the track width, therebyincreasing the recording density. A method which provides a thin filmmagnetic head having a width at the magnetic pole end, that is, a trackwidth, of 2 μm or narrower is described in Japanese Patent ApplicationLaid-Open No. 7-296328. According to the method described in thispublication, when a magnetic film is formed by plating, a silicondioxide layer is used as a plating frame. It is described in thepublication that the magnetic pole layers from the ABS to the zerothroat level in the rear part are wider than a magnetic pole end layerand are in parallel, and that a parallel path is formed for receivingand transferring the magnetic flux from/to the magnet pole end region,thereby enhancing the magnetic flux transmitting ability. Further, theshape of the upper magnetic film (shown by P2(T) in FIG. 24 and P2 inFIG. 25) is clearly shown in the head construction diagram of FIGS. 24and 25 of the publication. The cross-sectional area of the uppermagnetic film is constant, when it is seen from the air bearing surfaceat the gap depth position (upper part of the frame).

[0004] It is an object of the invention to provide a thin film magnetichead with less blur having a high recording magnetic field, and arecording/reproduction separation type magnetic head using the thin filmmagnetic head as well as a magnetic recording and reproducing apparatus.

[0005] It is another object of the invention to provide a high-frequencydriven magnetic head having a magnetic pole width of 1 μm or narrowerand a magnetic recording and reproducing apparatus which uses themagnetic head and has a very high recording density.

SUMMARY OF THE INVENTION

[0006] According to the invention, there is provided a thin filmmagnetic head having an upper magnetic film and a lower magnetic filmdisposed on either side of a non-magnetic gap film, wherein on at leastone of the upper and lower magnetic films, an upper end part magneticfilm is formed on the upper magnetic film and a lower end part magneticfilm is formed on the lower magnetic film via the magnetic gap at theends in which the magnetic gap is formed on the magnetic gap side.

[0007] The invention is also characterized in that a cross-sectionalarea parallel to the air bearing surface of at least one of the upperand lower end part magnetic films is smaller than the cross-sectionalarea of the upper and lower magnetic films in a part having the magneticgap; the track width of at least one of the upper and lower end partmagnetic films is narrower than the track width of the upper magneticfilm and that of the lower magnetic film; and at least one of the upperand lower end part magnetic films is projected more than the upper andlower magnetic films on the air bearing surface toward the air bearingsurface side.

[0008] According to the invention, the thin film magnetic head asmentioned above is characterized by either one of the following twofeatures or the combination thereof; i.e., (1) the fact that each of theupper and lower end part magnetic films is constructed by a platedmagnetic film having a saturated magnetic flux density of 1.5 tesla orhigher and the upper magnetic film is formed by plating or sputtering soas to have the width wider than a frame width of the plated magneticfilm and a specific resistance of 50 μΩ·cm or higher; and (2) the factthat the upper and lower end part magnetic films have the same trackwidth, an upper shield film for magnetically shielding the uppermagnetic film and a magnetic resistive film has a width wider than thetrack width, and the upper magnetic film is constructed by one or aplurality of multilayered magnetic films.

[0009] According to the invention, there is provided arecording/reproduction separation type magnetic head, in which arecording head for writing information and a reproduction head forreading information are integrally formed, wherein the recording head,is constructed in the form of the above mentioned thin film magnetichead.

[0010] In the above mentioned recording/reproduction separation typemagnetic head according to the invention, the reproduction head includesa ferromagnetic layer having a magnetic resistive effect and anantiferromagnetic layer which is closely attached to the ferromagneticlayer and allows the ferromagnetic layer to exhibit one-way anisotropy,and the antiferromagnetic layer is made of a Cr—Mn alloy.

[0011] According to the invention, a magnetic recording/reproductionapparatus, which comprises a thin film magnetic disk, on whichinformation is recorded, rotating means for the thin film magnetic disk,a recording/reproduction separation type magnetic device which isattached to a floating type slider and has a recording head for writinginformation and a reproduction head for reading information, and movingmeans for supporting the floating type slider and accessing the thinfilm magnetic disk; wherein, the magnetic disk, rotating at 4000 rpm orhigher for recording and reproduction and having a recording frequencyof 45 MHz or higher, is characterized in that it is accessed by arecording/reproduction separation type magnetic head constructed usingthe foregoing recording/reproduction separation type magnetic head.

[0012] Preferably, the invention is applied to a magnetic disk apparatushaving a recording density of 4 Gb/in² or higher When a recording headis seen from the air bearing surface, as shown in FIG. 1, the trackwidth of the magnetic film 1 above the gap is narrowed relative to atrack width Tw near the gap, and the upper end part magnetic film 16shown in FIG. 2 is widened on both sides of the track by the length t ofthe overhang. A frame member having an undercut is fabricated by thecombination of irradiation of ultraviolet rays and far ultraviolet raysand two stages of development of a two-layered film using a photo resistand polydimethylglutarimide; a gap film is formed between the photoresist layers; and the lower magnetic film is undercut.

[0013] When a magnetic head having the structure, as shown in FIG. 3according to the invention, is fabricated, since a frame member made ofsilicon dioxide or the like is not used, the wear resistance and anapparatus for forming the frame member become unnecessary. Since theupper magnetic film 11 is not exposed to the air bearing surface, asshown in FIG. 3, there is little leakage of the magnetic flux from theupper magnetic film to the air bearing surface, so that blur on themedium can be reduced. As shown in FIG. 6, when the shape of the uppermagnetic film is changed in the throat height, the cross-sectional areaon the air bearing surface side parallel to the air bearing surface isreduced, which is enlarged from the middle of the throat height.Consequently, the magnetic field which leaks from the upper magneticfilm 11 to the air bearing surface is reduced, and the magnetic fieldwhich leaks from the upper magnetic film 11 via the upper end magneticfilm 17 can be increased. The head can be used for a magnetic recordingapparatus of high recording density having a surface recording densityof 4 Gb/in² or higher. It is very important for the narrow track head tohave a reduced overhang t near the air bearing surface of the uppermagnetic film. In accordance with the invention, by setting the overhangat five times or smaller of the thickness of the gap film 17, the bluris reduced.

[0014] As an example, in the case where the track width (Tw) is 1.0 μm,the thickness (pu) of the upper magnetic film is 4 μm and the thicknessof the gap film is 0.2 μm, the relation between the magnetic field Hwhich leaks from the end of the upper magnetic film 11 and the overhangt is as shown in FIG. 7. The smaller the leakage magnetic field is, thebetter. However, as the overhang t is reduced, the magnetic fieldstrength near the gap on the air bearing surface decreases when thethickness of the upper magnetic film is made constant. In order toincrease the magnetic field strength and to reduce the leakage magneticfield, a range of t in which H≦1000 Oe in this case, that is, t≦1 μm, isdesirable and a value of five times as thick as the thickness (0.2 μm)of the gap film or smaller is desirable. In order to enhance themagnetic field strength when t≦1 μm, it is sufficient to increase thethickness of the upper magnetic film 11. When the thickness of the uppermagnetic film 11 is increased, the shape and the accuracy of a platingframe for forming the upper magnetic film 11 become a problem. That is,when the plating frame becomes thick, it is difficult to control theshape thereof and the accuracy of positioning relative to the magneticfilm (upper end part magnetic film 16) thereunder becomes a problem.Consequently, from the point of view of the shape and the accuracy ofthe plating frame, it is difficult to realize t=0 μm. It is preferableto select t=0.05 to 0.1 μm and increase the thickness of the uppermagnetic film 11. The above described example relates to the case wherethe upper magnetic film 11 is spaced from the air bearing surface by 10nm. However, if the upper magnetic film 11 is spaced from the airbearing surface by more than 10 nm, the magnetic field on the airbearing surface from the upper end part magnetic film is reduced. Bychanging the structure of the conventional recording head, as shown inFIG. 2, according to the structure of the invention, as shown in FIG. 3,the erasure of recording data and undesirable influence on adjacenttracks due to the magnetic field leaking from the upper end partmagnetic film are prevented. Effects similar to those of the structureas shown in FIG. 3 can be obtained by enlarging the cross-sectional areaof the upper magnetic film 11 in a position less than the gap depth (thewidth of the gap film in FIG. 3 from the air bearing surface) which isspaced from the air bearing surface and by reducing the cross-sectionalarea on the air bearing surface.

[0015] According to the invention, a magnetic pole end part of therecording head of the thin film magnetic head is fabricated by frameplating. That is, the three kinds of films which make up the upper endpart magnetic film 16, the gap film 17 and the lower end part magneticfilm 18, as shown in FIGS. 2 and 3, are plated by using the same frame.The upper magnetic film 11 as shown in FIGS. 2 and 3 is in contact withthe upper end part magnetic film 16 on the air bearing surface side.According to the conventional structure, the shape of the upper end partmagnetic film 16 is as shown in FIG. 2 in cross section in the verticaldirection to the air bearing surface and is as shown in FIG. 4 when seenfrom above the film face. As shown in FIG. 4, the shape of the gap film17 and that of the upper end part magnetic film 16 are the same untilthe gap depth (frame end) from the air bearing surface, and the crosssection parallel to the air bearing surface is the same from the airbearing surface to the gap depth (cross section of the location wherethe gap film exists). In contrast to the conventional shape as indicatedabove, as shown in FIG. 5 or 6, the cross-sectional area of the upperend part magnetic film 16 on the air bearing surface side is reduced,whereby the magnetic field leaking from the upper end part magnetic film16 is reduced on the air bearing surface, so that the recording magneticfield becomes sharp, the magnetic field distribution of the track edgebecomes sharp, and the background is reduced.

[0016] As an antiferromagnetic film, an oxide nickel film, aniron-manganese alloy thin film, a chromium-manganese,chromium-manganese-platinum, chromium-aluminum alloy film or the likecan be used. A hard magnetic film, such as a ferromagneticcobalt-platinum, cobalt-chromium-platinum or iron-cobalt-terbium alloyfilm can be also used. The hard magnetic film is a magnetic film whosemagnetization is not easily changed by an external magnetic field. Sincethe direction of magnetization is hardly changed even when a magneticfield of 50 oersted, where the coercive force is for example 100 oerstedor larger, is applied, effects similar to those of the antiferromagneticfilm can be obtained. That is, as long as a film has a characteristicthat one-way anisotropy by a switched connection bias can be applied,when the film is formed so as to be closely attached to another magneticfilm, the film does not always have to be antiferromagnetic. It ispreferable to use a film generally called a bias film.

[0017] As the magnetic film, it is preferable to use an alloy of Ni 70to 95 at %, Fe 5 to 30 at %, and Co 1 to 5 at % or an alloy of Co 30 to85 at %, Ni 2 to 30 at % and Fe 2 to 50 at %. In addition, a Permalloyor Permender alloy or the like can be used. That is, it is preferable touse a ferromagnetic material having a preferable soft magneticcharacteristic.

[0018] Preferably, the non-magnetic conductive film is made of Au, Ag orCu. Further, Cr, Pt, Pd, Ru, Rh or the like, or an alloy thereof can bealso used. That is, it is preferable to use a material which does nothave spontaneous magnetization at a room temperature and has preferablepermeability of electrons. The thickness of each of the above films ispreferably about 2 to 1000 Å.

[0019] The invention relates to a magnetic head comprising a coilconductor sandwiched by a first magnetic film and a fourth magneticfilm, a second magnetic body magnetically coupled with the firstmagnetic film and a third magnetic body magnetically coupled with thefourth magnetic film, and a magnetic gap sandwiched between the secondmagnetic film and the third magnetic film. In the structure forrealizing both a high frequency characteristic and narrow tracks, whichwill be described hereinafter, especially to reduce the manufacturingcosts, an insulative and non-magnetic film which is exposed to a slidingface includes at least the first magnetic film.

[0020] In order to satisfy the fundamental functions of a magnetic headhaving the above structure, a part of the third magnetic film is exposedto the non-magnetic and insulative film face, and the third and fourthmagnetic films are magnetically coupled.

[0021] In order to reduce the manufacturing costs of the magnetic head,at least three sides of each of the second and third magnetic films forforming a magnetic gap are surrounded by a non-magnetic and insulativefilm, on the surface of which a second non-magnetic and insulative filmis deposited, and a coil conductor is provided in the secondnon-magnetic and insulative film.

[0022] In order to reduce the manufacturing costs, the second magneticfilm and the third magnetic film have the same two-dimensional shape,and a magnetic pole part for specifying a write track width and a backcontact part for magnetically connecting the first and fourth magneticfilms are constructed in the laminated structure of the second and thirdmagnetic films.

[0023] In order to improve the high frequency characteristic, a coilconductor is arranged on the outside of the region, in which the secondand third magnetic films exist.

[0024] In order to improve the high frequency characteristic, thespecific resistance of the first and fourth magnetic films is madehigher than that of the third magnetic film.

[0025] In order to improve the high frequency characteristic, the volumeof the third magnetic film is made 10E-4 or smaller as compared to thevolume of the first and fourth magnetic films.

[0026] In order to improve the high frequency characteristic and toallow a write magnetic field of the necessary intensity to be generated,the relation of 0.8<BS1×t/Bs2×Dg<1.5 is satisfied, where Bs1 denotes thesaturable magnetic flux density of the fourth magnetic film, t the filmthickness, Bs2 the saturable magnetic flux density of the third magneticfilm and Dg the overlapped length in the floating direction of the thirdand fourth magnetic films.

[0027] In order to reduce the unnecessary write phenomenon to anadjacent track and to realize high density recording, the area of thesecond and third magnetic films exposed to the air bearing surface ofthe head is made larger than the area of the first and fourth magneticfilms, which are also exposed.

[0028] In order to improve the high frequency characteristic, therelation of ρ/(μ×t2)>0.0064 is satisfied, where ρ(μΩ·cm) denotes aspecific resistance of the material used to form the first and fourthmagnetic films, μ is the relative magnetic permeability at 5 MHz and t(μm) is the film thickness.

[0029] A magnetic head, which satisfies the above mentioned condition,is fabricated and a magnetic recording apparatus is assembled by usingthe magnetic head.

[0030] By supplying a control signal at a driving frequency of 150 MHzor higher to a magnetic recording apparatus having a magnetic head withthe improved frequency characteristic, the magnetic recording apparatuscan be driven at the above driving frequency.

[0031] In order to realize high density recording, the width of thethird magnetic film exposed to the sliding surface is made 1.0 μm ornarrower. In order to satisfy the frequency characteristic and thenecessary write magnetic field intensity, the thickness is made 1.0 μmor thinner. Such a magnetic head is fabricated and a magnetic recordingapparatus having the magnetic head is assembled.

[0032] In order to satisfy the requirements for reliability and the lifeof a recording apparatus, the first insulative and non-magnetic film asmentioned above is formed of an alumina film or a film containingdiamond particles as a main component.

[0033] In order to realize both a high frequency characteristic and thenecessary write magnetic field intensity, each of the first and fourthmagnetic films is composed of a multilayered film, in which a magneticfilm and a non-magnetic film are laminated, or a high-electric resistiveamorphous alloy film having a specific resistance of 50 μΩ·cm or higher.Further, the third magnetic film is formed of an alloy film whose maincomponent is Co—Ni—Fe having a specific resistance of 20 μΩ·cm or lower.Moreover, by mounting the magnetic head having the above structure on arecording apparatus, a high-speed and high- density magnetic recordingapparatus is realized.

[0034] In order to reduce the manufacturing costs and to improve thefrequency characteristic, the first and second magnetic films are madeof the same material. By mounting the magnetic head on a magneticrecording apparatus, a high-speed magnetic recording apparatus cab becheaply manufactured.

[0035] In order to realize both a reduction in manufacturing costs andthe necessary write magnetic field intensity, the saturable magneticflux density of the third magnetic film is made higher than that of thesecond magnetic film. This construction is used under the condition thatthe third magnetic film is positioned on the side of an outflow endalong the rotating direction of a medium with respect to the secondmagnetic film.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is a diagram illustrating the shape of a magnetic film, asseen from the air bearing surface side of a magnetic recording headhaving an overhang;

[0037]FIG. 2 is a cross section of the magnetic recording head, as seenfrom a face perpendicular to the air bearing surface;

[0038]FIG. 3 is a cross section of the magnetic recording head, as seenfrom a face perpendicular to the air bearing surface;

[0039]FIG. 4 is a diagram illustrating the shapes of an upper magneticfilm and an upper end part magnetic film, as seen from above in amagnetic recording head;

[0040]FIG. 5 is a diagram illustrating the shapes of the upper magneticfilm and the upper end part magnetic film, as seen from above in amagnetic recording head;

[0041]FIG. 6 is a diagram illustrating the shapes of the upper magneticfilm and the upper end part magnetic film, as seen from above in amagnetic recording head;

[0042]FIG. 7 is a graph showing the relation between the magnetic field(H) and the overhang (t);

[0043]FIG. 8 is a perspective view, partly in cross-section of a part ofa recording/reproduction separation type magnetic head;

[0044]FIG. 9 is a plan view of a thin film magnetic head for recording;

[0045]FIG. 10 is a perspective view showing the film construction of amagnetic resistive head;

[0046]FIG. 11 is a diagram showing the film structure of a magneticresistive head;

[0047]FIG. 12A is a plan view and FIG. 12B is a cross-sectional view ofa magnetic recording and reproducing apparatus;

[0048]FIG. 13 is a diagram showing the principle of operation of amagnetic recording and reproducing apparatus;

[0049]FIG. 14 is a cross section of a magnetic recording head;

[0050]FIG. 15 is a cross section of a magnetic recording head;

[0051]FIGS. 16A, 16B and 16C are conceptual diagrams showing a magnetichead of the invention;

[0052]FIGS. 17A to 17F are diagrams showing the process according to amethod of fabricating a magnetic head of the invention;

[0053]FIGS. 18A to 18C are diagrams illustrating various shapes of amagnetic film pattern according to the invention;

[0054]FIG. 19 is a frequency characteristic diagram, showing what occurswhen the specific resistance of the first and fourth magnetic filmpatterns is changed;

[0055]FIG. 20 is a graph showing the relation between the specificresistance of a core and the upper limit of the driving frequency;

[0056]FIG. 21 is a cross section of the construction of a magnetic headof the invention;

[0057]FIG. 22 is a graph showing the relation among the magnetic polecondition, the magnetic field intensity, and the magnetic fieldgradient;

[0058]FIG. 23 is a graph showing the relation between the volume of thethird magnetic film and the frequency characteristic; and

[0059]FIG. 24 is a graph showing the relation between the volume of thethird magnetic film and the upper limit of a writable frequency.

DESCRIPTION OF THE EMBODIMENTS Embodiment 1

[0060]FIG. 3 shows a cross section of a recording head portion of arecording/reproduction separation type magnetic head of the invention.

[0061] As shown in FIG. 3, the invention relates to the recording head.In a thin film magnetic head having an upper magnetic film 11 and lowermagnetic film 15 sandwiching a non-magnetic gap film 17, an upper endpart magnetic film 16 is formed on the upper magnetic film 11 in the endpart where the magnetic gap 17 is formed.

[0062] According to the invention, the area of the cross sectionparallel to the air bearing surface of the upper end part magnetic film16 is smaller than that of the cross section in the part having themagnetic gap of the upper magnetic film 11.

[0063] The track width Tw of the upper end part magnetic film 16 isnarrower than the track width Tw of the upper magnetic film 11.

[0064] Further, according to the invention, the upper end part magneticfilm 16 is projected to the air bearing surface side on the air bearingsurface from the upper magnetic film 11.

[0065] The thin film magnetic head of the invention comprises the upperend part magnetic film, which is made of a grated magnetic film having asaturable magnetic flux density of 1.5 tesla or higher, and the uppermagnetic film having a width wider than the frame width of the platedmagnetic film and a specific resistance of 50 μΩ·cm or higher, which isformed by plating or sputtering.

[0066] Further, according to the invention, the track width of the upperend part magnetic film 16 and that of the lower end part magnetic film18 are equal, the upper shielding film for magnetically shielding theupper magnetic film and the magnetic resistive film has a width widerthan the track width, and the upper magnetic film 11 can be constructedby a multilayered magnetic film.

[0067] Although not shown, the invention relates to arecording/reproduction separation type magnetic head in which arecording head for writing information and a reproduction head forreading information are integrally formed.

[0068] A process for fabricating a recording head according to theinvention will be described hereinbelow. Below the lower magnetic film15, as shown in FIG. 3, a giant magnetic resistive effect head existsvia a gap film. The lower magnetic film 15 serves as a shield from thegiant magnetic resistive effect head. When a magnetic tunnel spin valve(giant magnetic resistive effect type using an oxide film) head isformed on the underside, it serves as a film available for use as both ashield and an electrode. For these films, a ferromagnetic film having ahigh permeability is used. A multilayered film of a ferromagneticmaterial containing Co, Ni, or Fe and an oxide film can be also used.Thereon, a frame is formed by a resist or a resist partially containingan oxide film, and a ferromagnetic film is electrically plated betweenframes, thereby forming the lower end part magnetic film 18. The throatheight is 10 μm or lower. For this plating film, a Co.Ni.Fe alloy, Co.Fealloy, Ni Fe alloy or an alloy obtained by adding a metalloid element toone of the above alloys is suitable. The gap film 17 is plated on thelower end part magnetic film 18. For the gap film 17, an alloy such asCr alloy or an alloy of Ta, W, Ti, Mo or the like is used. On the gapfilm 17, the upper end part magnetic film 16 is plated. The magneticcharacteristic necessary for the plating film which is in contact withthe gap film is that the saturable magnetic flux density is high. Byusing a film having a saturable magnetic flux density of 1.5 T orhigher, a recording of 4 Gb/in² can be achieved. A magnetic film similarto that of the lower end magnetic film 18 may be used as the upper endpart magnetic film 16. In order to fabricate a recording head having theconstruction as shown in FIG. 5, after removing the frame, the lowerinsulating film 14 is formed, on which coil 13 is formed, and afterthat, the upper magnetic film is deposited on insulating film 12 byplating or sputtering. The magnetic characteristic necessary for theupper magnetic film is high in specific resistance. The film has to havea specific resistance of 50 μΩ·cm or higher and a saturable magneticflux density of 1.0 T or higher. It was confirmed that when the trackwidth is 0.5 μm, a recording magnetic field of 2000 Oe or higher wasgenerated by combining the aforesaid characteristic of the plating filmand that of the upper magnetic film (it is desirable that thecharacteristic of the lower magnetic film 15 is the same as that of theupper magnetic film). It was also confirmed that the recording headhaving the construction of FIG. 5 or 6 has less blur as compared withthat of the construction of FIG. 4, while there was no outstandingdifference in the recording magnetic field intensity. Since the value ofthe magnetic field intensity also depends on the saturable magnetic fluxdensity of the upper magnetic film 11, it is desirable that thesaturable magnetic flux density of the upper magnetic film is higher. Itis confirmed that there is such an effect, when the position on the airbearing face side of the upper magnetic film of the head having theconstruction of FIG. 5 is spaced from the air bearing face by 10 nm ormore. Also in case of FIG. 6, the effect was confirmed, when theposition of the upper magnetic film is spaced from the air bearing faceby 10 nm. The value of the overhang t lies within a range from 10 nm to100 μm.

[0069] As shown in FIGS. 5 and 6, the upper magnetic film .1 has arounded Erlenmeyer flask shape which is narrowed toward the end part asan air bearing surface.

[0070]FIG. 8 is a perspective view showing the construction of therecording/reproduction magnetic head near the air bearing surface. Giantmagnetic resistive effect film 104 is arranged between lower shield film106 and upper shield film 108 via insulating films, and a sense currentflows via electrode 105. The recording head is constructed by forminglower end part magnetic film 103, gap film 102, upper end part magneticfilm 101, upper magnetic film 107 and coil 109 on the upper shield film108. The upper magnetic film 107 is formed in a position at a specifieddepth (10 nm or more) from the air bearing surface. With such aconstruction, the isomagnetic lines of the magnetic field around the airbearing surface of the gap film 102 are not so greatly influenced by theend part of the upper magnetic film 107, so that a high magnetic fieldgradient and preferable recording characteristics can be obtained.

[0071] In this embodiment, a film having a high specific resistance asdescribed before is used for a recording head, and the recording headand a reproduction head to be described hereinbelow are combined. Thegiant magnetic resistive effect film 104 is used for a reproductionhead, and the electrode 105 for carrying a current is electrically incontact with the giant magnetic resistive effect film 104. Under theelectrode 105 and the giant magnetic resistive effect film 109, there isdisposed a lower shield film 106 via a lower gap film. On the giantmagnetic resistive effect film 104, the lower magnetic film 108 having ahigh specific resistance to function as the upper shield film is formedvia an upper gap film, which is made a part of the lower magnetic poleof the recording head. The high frequency characteristic of therecording head can be improved by using a part of the lower magneticfilm 108 having a high specific resistance as a high specific resistancefilm. It is preferable that the width of the gap film 102 of therecording head is equal to that of each of the upper and lower magneticfilms, and that the upper and lower films 101 and 103 having a highsaturable magnetic flux density are made of a material having asaturable magnetic flux density higher than the other parts of themagnetic pole. The upper magnetic film 107 having a high specificresistance is formed on the high saturable magnetic flux density film101. A current is caused to flow in the coil 109 of the recording headand data is recorded in recording medium 110 by the magnetic field fromthe recording head. A head having another construction using aferromagnetic tunnel film can be also used as a reproduction head.

[0072]FIG. 9 shows a plan view of the recording head part of FIG. 8,when seen from above. The upper magnetic film 107 has a shape in whichthe aforesaid upper end part magnetic film is projected on the airbearing surface and has a plane shape of a rounded Erlenmeyer flask inwhich the end is narrowed. The coil 109 is wound like a spiral as shownin the plan view and is connected to outer lead 32 by connection part31. The upper shield film 108 serves as a lower magnetic film. The lowerend part magnetic film is formed on the end of the upper shield film 108in contact with the gap film 102.

[0073]FIG. 10 is a perspective view of an element having a spin valvemagnetic resistive film which is used for the reproduction head of therecording/reproduction separation type magnetic head of the invention.

[0074] An MR sensor of the invention has a construction wherein a firstmagnetic layer 45 of soft ferromagnetic material, a non-magnetic metallayer 21, and a second magnetic layer 22 of ferromagnetic material aredeposited on proper substrate 43 made of glass, ceramics or the like.The ferromagnetic layers 45 and 22 are arranged so that theirmagnetization directions have an angle difference of about 90 degree,when no magnetic field is applied. Further, the magnetization directionof the second magnetic layer 22 is fixed to the same direction as thatof the magnetic medium. The magnetization direction of the firstmagnetic layer 45 of soft ferromagnetic material when no magnetic fieldis applied is inclined from the magnetization direction of the secondmagnetic layer by 90 degrees. The magnetization rotation occurs in thefirst magnetic layer 45 in response to an applied magnetic field.

[0075] The first magnetic layer 45, the non-magnetic motel layer 21, thesecond magnetic layer 22 and the antiferromagnetic layer 23 in theembodiment can be constructed according to a laminated construction asshown in FIG. 11, which will be described hereinafter. Hardferromagnetic layer 47 can be made of Co₈₂.Cr₉.Pt₉, Co₈₀.Cr₈.Pt₉(ZrO₂)₃or the like. The film construction of FIG. 16 corresponds to that of thefirst magnetic layer 45 and the second magnetic layer 22 in theembodiment, and the magnetization directions are the same as describedabove.

[0076] According to the invention, before depositing the first magneticlayer 45 of soft ferromagnetic material, proper lower layer 24 made ofTa, Ru or Crv, for example, is deposited on the substrate 43. Thepurpose of deposing the lower film 24 is to optimize the structure,crystal grain size and shape of a layer to be deposited later. The shapeof the layer is very important in order to obtain a large MR effect.This is because a very thin spacer layer can be used as the non-magneticmetal layer 21, depending on the shape of the layer. In order tominimize the influence caused by a shunt current, it is preferable thatthe lower electrode has a high electric resistance. The lower layer canalso have an inverse structure as mentioned above. The substrate 43 hasa sufficiently high electric resistance and is sufficiently flat. In thecase where the substrate 43 has a proper crystal construction, the lowerfilm 24 may be unnecessary.

[0077] In the first magnetic layer 45, there is used means forgenerating a bias in the vertical direction for holding a single domainstate in the direction parallel to the surface of the drawing. As meansfor generating a bias in the vertical direction, there can be used thehard ferromagnetic layer 47 having a high saturable coercive force, ahigh perpendicularity and a high electric resistance. The hardferromagnetic layer 47 is in contact with the region of the end part ofthe first magnetic layer 45 of the soft ferromagnetic material. Themagnetizing direction of the hard ferromagnetic layer 47 is in parallelto the surface of the drawing.

[0078] The antiferromagnetic layers can be adhered to the region of theend part of the first magnetic layer 45, and the necessary bias in thevertical direction is generated. It is preferable that theseantiferromagnetic layers have a blocking temperature sufficientlydifferent from that of the antiferromagnetic layer 23 used for fixingthe magnetizing direction of the second magnetic layer 22 of theferromagnetic material.

[0079] Preferably, a capping layer made of a material having a highresistance, such as Ta, is applied on the whole MR sensor. Electrode 28is provided, and circuits are formed among the MR sensor structure, thecurrent source and detecting means.

[0080]FIG. 11 shows films constructing a magnetic resistive device ofthe invention, which are formed in place of the non-magnetic metal layer21, the second magnetic layer 22 and the antiferromagnetic layer 23, asshown in FIG. 10 and were fabricated as follows by a high-frequencymagnetron sputtering apparatus. In an atmosphere of argon at 3millitorr, the following materials are sequentially deposited on aceramic substrate having a thickness of 1 mm and a diameter of 3 inches.As sputtering targets, a tantalum, nickel −20 at % iron alloy and acopper, cobalt, chromium −50 at % manganese are used. Achromium-manganese alloy film is produced in such a manner thatcm-square chips as an additional element are arranged on thechromium-manganese target and the composition is adjusted by increasingor decreasing the number of chips. When a Co—Fe—Ni layer is formed as aferromagnetic layer, the composition is adjusted by arranging cm-squarechips of nickel and iron on a cobalt target.

[0081] The laminated films are formed as follows. High frequencyelectric power is applied to a cathode, in which each target isarranged, and a plasma is generated in the apparatus. A respectiveshutter arranged for every cathode is opened and closed sequentially,whereby the layers are sequentially deposited. When the film is formed,a magnetic field of about 30 Oe is applied in parallel to the substrateby using a permanent magnet, thereby obtaining uniaxial anisotropy andleading the direction of an exchange and coupling magnetic field of thechromium-manganese film toward the direction of the applied magneticfield.

[0082]FIGS. 12A and 12B show an example of a magnetic disk apparatususing the recording/reproduction separation type magnetic head of theinvention. Recording/reproduction separation type magnetic head 40 isprovided on a slider made from sintered material of A1 ₂O₃₁ floatedabove a thin film magnetic disk 51 serving as a recording medium whichis rotated by a spindle 52, and positioned by head positioning mechanism53 with high accuracy. A reproduction signal and a recording signal readby the recording/reproduction separation type magnetic head 40 areprocessed by a recording/reproduction signal processor 55.

[0083]FIG. 13 is a diagram showing the operational principle of amagnetic disk apparatus using the recording/reproduction separation typemagnetic head as shown in FIG. 12A. Head positioning mechanism 202positions recording/reproduction separation type magnetic head 201 abovea magnetic disk serving as recording medium 203, which is rotated by amotor. The recording/reproduction separation type magnetic head 201 isconnected to reproduction signal processing system 204.

[0084] The apparatus includes a DC motor for rotating the magnetic disk,the magnetic head for writing and reading information, a positioningdevice, that is, an actuator and a voice coil motor, for positioning themeans which supports the magnetic head and changes the position thereofwith respect to the magnetic disk, an air filter for keeping the insideof the apparatus clean, and the like. The actuator has a carriage, arail and a bearing. The voice coil motor includes a voice coil and amagnet. In FIG. 12B, there is shown a case where eight magnetic disksare attached to the same rotary shaft to increase the total storagecapacity.

[0085] As the magnetic disk, there is used a medium having a preferablesurface condition in which the surface roughness R_(MAX) is 100 Å orsmaller, preferably 50 Å or smaller. On the magnetic disk, a magneticrecording layer is formed on the surface of the rigid substrate by avacuum film formation method. As the magnetic recording layer, amagnetic thin film is used. Since the thickness of the magneticrecording layer formed by the vacuum film formation method is 0.5 μm orless, the surface condition of the rigid substrate is reflected as asurface condition of the recording layer. Consequently, the rigidsubstrate having a surface roughness R_(MAX) of 100 Å or smaller isused. As such a rigid substrate, rigid substrate material containingglass, chemically strengthened soda aluminosilicate glass or ceramics asa main component is suitable.

[0086] When the magnetic layer is made of a metal or an alloy,preferably, an oxide layer or a nitride layer is deposited on thesurface or the surface is oxidized. It is also desirable to use a carbonprotective layer or the like. With these, the durability of the magneticrecording layer is improved. Even when recording and reproducingoperations are executed with an extremely small floating amount and evenat the time of contact, start and stop, the magnetic disk is preventedfrom being damaged.

[0087] When the performance (overwrite characteristic) of the recordinghead according to the invention was measured, an excellent recordingperformance of about −50 dB was obtained even in a high frequency areaof 40 MHz or higher.

[0088] According to the embodiment, a high-sensitive MR sensor can beobtained, in which the recording can be sufficiently performed also fora medium having a high coercive force even in a high frequency area, andwhich has a media transfer speed of 15 MB/seconds or higher, a recordingfrequency of 45 MHz or higher, a high-speed transfer of data of 4000 rpmor higher of the magnetic disk, a reduction in the access time, anincrease in the recording capacity and excellent MR effects based on ananisotropic magnetic resistive effect. Thus, a magnetic disk apparatushaving a surface recording density of 3 Gb/in² or higher can beobtained.

Embodiment 2

[0089]FIG. 14 shows a cross section of a thin film magnetic head forrecording, which has an upper magnetic film 11 and a lower magnetic film15 spaced via a non-magnetic gap film 17 in place of the arrangement ofFIG. 3. The lower end part magnetic film 18 is, via the magnetic gap,formed on the magnetic gap side of the lower magnetic film 15 in the endpart where the magnetic gap is formed.

[0090] The area of the cross section, which is in parallel to the airbearing surface, of the lower end part magnetic layer is smaller thanthat of the lower magnetic film in the part having the magnetic gap.

[0091] The width of the lower end part magnetic film is narrower thanthat of the lower magnetic film. The lower end part magnetic film isprojected from the lower magnetic film toward the air bearing surfaceside.

[0092] The lower end part magnetic film in this embodiment isconstructed by a plated magnetic film having a saturable magnetic fluxdensity of 1.5 tesla or more. The lower end magnetic film is formed byplating or sputtering so as to have a width wider than the frame widthof the plated magnetic film and a specific resistance of 50 μΩ·cm orhigher.

[0093] The upper end part magnetic film 16 and the lower end partmagnetic film 18 have the same track width. The upper shield film formagnetically shielding the upper magnetic film and the magneticresistive film is wider than the track width, and the upper magneticfilm can be formed as a multilayered magnetic film.

Embodiment 3

[0094] Similarly to the above, FIG. 15 shows a cross section of a thinfilm magnetic head, which has an upper magnetic film 11 and a lowermagnetic film 15 spaced via the non-magnetic gap film 17 in place of thearrangement of FIG. 3. The upper end part magnetic film and the lowerend part magnetic film are, via the magnetic gap, formed on the magneticgap side of the upper magnetic film 11 and the lower magnetic film 15 inthe end part where the magnetic gap is formed, respectively.

[0095] The areas of the cross sections parallel to the air bearingsurface of the upper and lower end part magnetic films are smaller thanthose of the cross sections in the parts where the magnetic gap isformed of the upper and lower magnetic films.

[0096] Further, the track width of each of the upper and lower end partmagnetic films is narrower than that of each of the upper and lowermagnetic films.

[0097] The upper and lower end part magnetic films on the air bearingsurface are projected toward the air bearing surface from the upper andlower magnetic films. Although the lower magnetic film 15 is slightlyprojected from the top of the upper magnetic film 11 in this embodiment,they can also have the same length.

[0098] Each of the upper and lower end part magnetic films is a platedmagnetic film having a saturable magnetic flux density of 1.5 tesla orhigher formed by plating or sputtering so as to have a width wider thanthe frame width of the plated magnetic film and a specific resistance of50 μΩ·cm or more.

[0099] Further, the upper and lower end part magnetic films have thesame track width. The upper shield film for magnetically shielding theupper magnetic film and the magnetic resistive film has a width widerthan the track width and the upper magnetic film is constructed by amultilayered magnetic film.

Embodiment 4

[0100]FIGS. 16A to 16C show an embodiment of a magnetic head to whichthe invention is applied. In the figures, FIG. 16A shows a cross sectionof the construction, FIG. 16B shows a plan view and FIG. 16C shows aplan view of the air bearing surface.

[0101] The first magnetic film described in accordance with theinvention corresponds to lower core 125 as shown. The fourth magneticfilm corresponds to upper core 127. Coil 126 exists between the firstand fourth magnetic films. The coil 126 is made of conductive materialhaving a thickness of 2 μm and whose main component is Cu, Au, Al, Ta,Mo and the like. Insulating material 138 is filled in order to maintainelectric insulation between the coil 126 and the core 127.

[0102] Second magnetic film 132 and third magnetic film 133 are insertedbetween the upper core 127 serving as the fourth magnetic film and thelower core 125 serving as the first magnetic film. A magnetic gap (orrecording gap) 110 is formed by those members. The constructionmentioned above is the same as that of a magnetic head according to theconventional technique.

[0103] In accordance with the invention, a notch structure described inthe conventional technique does not exist. Instead, non-magnetic film131 having a single structure which is in contact with second magneticfilm pattern 132 and third magnetic film pattern 133 is provided. Thenon-magnetic film 131 covers at least almost the whole of the firstmagnetic film.

[0104] The coil 126 is embedded in the insulating material 138 depositedon the non-magnetic insulating film 131.

[0105] Magnetic path members 141 and 142 and magnetic gap 140 areprovided between the upper core 127 and the lower sore 125. Thisconstruction is preferable, when a hard film, such as an alumina film,is used as the insulative and non-magnetic film 131 and has theadvantage of providing a reduction in the manufacturing costs.

[0106] Namely, the alumina film is formed by the sputtering or the like.When, however, the alumina film is formed, it is also deposited on thethird magnetic film. In order to achieve the fundamental functions ofthe magnetic head, it is needless to say that the alumina film has to beselectively removed from the third magnetic film. However, there is aproblem in that the alumina film is hard. By employing the constructionof the invention, this process will be performed by a method at lowcost, which will be described hereinafter.

[0107] By forming the members (140, 141, and 142) simultaneously withthe second magnetic film 132 and the third magnetic film 133, anincrease in the manufacturing costs can be prevented.

[0108] Reference numeral 137 in the drawing denotes a member (protectivefilm) for protecting the magnetic head functional part, 138 denotes anelectric insulating layer, 130 denotes an electrode for flowing a writecurrent through the coil, and 136 denotes a magnetic head body (slider).

[0109]FIG. 16B shows the magnetic head as seen from the side of theupper core corresponding to the fourth magnetic film. From the drawing,it is seen that the coil 126 is wound like a spiral. The coil 126 isconnected to the electrode 130 (in FIG. 16A) via contact hole 134. Inthis case, the coil conductor 126 is arranged outside of the regions inwhich the second magnetic film 132 and the third magnetic film 133exist, in order to improve the high frequency characteristic. The uppercore 127 and the lower core 125 are coupled in magnetic contact hole135. The magnetic contact hole 135 has the above mentioned constructionincluding the magnetic path materials 141 and 142 as described above.

[0110] The second magnetic film 132 and the third magnetic film 133,representing the features of this magnetic head, are positioned at theends of the fourth magnetic film 127 and the first magnetic film 125(ends close to a recording medium), and a part thereof is exposed to thesliding face (strictly, it is often via a sliding face protectivelayer). FIG. 16C shows the construction of the members, when viewed fromthe α direction. That is, the second magnetic film 132 and the thirdmagnetic film 133, which are narrow, are sandwiched by the fourthmagnetic film 127 and the first magnetic film 125.

[0111] The second magnetic film 132 is magnetically coupled to the firstmagnetic film 125, and the third magnetic film 133 is magneticallycoupled to the fourth magnetic film 127 (magnetically coupling means astate where the magnetic path resistance is small). A magnetic gap isformed between the second magnetic film 132 and the third magnetic film133. Although the magnetic gap length is 0.3 μm in this embodiment, itis obviously understood that the invention can be also applied to otherconditions. As the magnetic gap, a non-magnetic film, such as a Cu film,an alumina film, a silicon oxide film or the like, can be used.

[0112] As shown in the drawing, the insulative non-magnetic film 131,representing a single construction film, is exposed to the slidingsurface. By using an alumina film or a film containing a small amount ofdiamond as the insulative non-magnetic film 131, the mechanical strengthcan be enhanced. Thus, a very reliable magnetic head can be realized.

[0113] In order to realize high density recording, the width of thethird magnetic film exposed to the sliding surface is set at 1.0 μm ornarrower, and in addition, the thickness of the third magnetic filmpattern is set at 1.0 μm or less in order to satisfy the frequencycharacteristic and the write magnetic field strength requirements.

[0114] An effect is obtained by using electrolyte plating for formingthe third magnetic film. Further, by constructing the magnetic poleunder conditions which will be described hereinafter, the magnetic headwhich can be also driven at a high frequency can be realized.

[0115] In accordance with the invention, the electric resistance of bothof the first and fourth magnetic films is selected to be rather high(specific resistance: 50 μΩ·cm or higher, the reason will be mentionedhereinafter). Specifically, the film is formed by a Co.Ta.Zr amorphousalloy film, a Sendust, a Co.Zr.Nb.Ta amorphous alloy film, amultilayered film and the like.

[0116] The film formation is performed by sputtering. The film patternis processed by a dry method such as a lift-off method and a dry etchingmethod. With respect to films each having a high specific resistance, itis difficult to form a pattern by electrolyte plating to have anexcellent fine processing ability. Consequently, it was consideredconventionally that application to a magnetic pole material having anarrowed magnetic pole width is difficult.

[0117] According to this construction, since such material is used onlyfor the part where the pattern area (pattern width) is wide, the patterncan be formed by the dry method. Since the magnetic film patterns have alarge area, the magnetic field necessary for the writing operation canbe led to the top of the magnetic pole (sliding surface side), withoutforcibly using material having a large saturable magnetic flux density.

[0118] In contrast to the second magnetic film, the third magnetic filmpositioned on the outflow end side (trailing side) is made of a materialhaving a saturable magnetic flux density of 1.5 T or more. This isbecause the magnetic field from the outflow end side exerts an influenceon the quality of magnetic domain information to be recorded into themedium (overwrite characteristic, magnetization inversion length and thelike). Simply stated, a function of generating a sufficient recordingmagnetic field is important. It is well known that a sufficientrecording magnetic field is generated from a material having a highsaturable magnetic flux density.

[0119] Specifically, the third magnetic film is made of an alloy ofCo.Ni.Fe, Ni.Fe, a pure iron, a nitride iron or the like. The electricresistance of each of those films is almost 50 μΩ·cm or lower, and filmshaving an electric resistance lower than that of each of the first andfourth magnetic films are selected, so that the film can be formed byelectrolyte plating in order to realize a high density recording.

[0120] A high-resistive film has the property that electricity is noteasily passed therethrough. Consequently, segregation easily occurs atthe time of electrolytic plating and a film of a good quality cannot begrown. Further, a film including an insulative substance cannot be grownby plating. For those reasons, a material having a low electricresistance and a high saturable magnetic flux density, which includes noinsulative substance, is selected for the third magnetic film.

[0121] Next, the reason why the specific resistance value of the firstand fourth magnetic films is set at 50 μΩ·cm or higher will bedescribed. FIG. 19 shows the result of measurement of the frequencycharacteristics of a magnetic head, while changing the specificresistance of the first and fourth magnetic films. An electron beamtomography method was used for the measurement. The relative magneticpermeability μ of the magnetic film was fixed to almost 1000. The filmthickness of each of the magnetic films was fixed to 2.8 μm. Theoverlapped part (Dg shown in FIG. 21) of the fourth and third magneticfilms was set to 2 μm.

[0122] It is understood from the graph that, in case of using materialhaving a specific resistance of 16 μΩ·cm (a general value of Ni.Fematerial), the magnetic field which is generated (leaked) is reduced to50% or lower at a driving frequency of 90 MHz as compared with theresult at the driving frequency of 10 MHz (almost equal to the result incase of a magnetostatic state). It is also understood that, in case ofmaterial having a specific resistance of 60 μΩ·cm or higher, reductionin the generated magnetic field is small and a strong magnetic fieldalmost to 200 MHz occurs.

[0123] In the magnetic disk apparatus, high-speed writing is demanded.In order to satisfy this demand, a magnetic head for generating a writemagnetic field at a high frequency is necessary. For this reason, amaterial having a high specific resistance is used for the first andfourth magnetic films.

[0124]FIG. 20 is a graph which is used to estimate the specificresistance of a core (corresponding to each of the first and fourthmagnetic films as described in accordance with the invention) which isnecessary for high frequency driving. The ordinate in the graph showsthe upper limit frequency (which can be obtained from FIG. 19) by which65% of a magnetic field at the time of a low frequency driving of about1 MHz can be obtained. The magnetic field of 65% is a value which is thelower limit value of a magnetic field necessary for a regular writingoperation and is obtained from experience gained in the manufacturing ofthe apparatus.

[0125] It is understood from the chart that driving at 150 MHz isenabled by increasing the specific resistance of the core to 50 μΩ·cm.

[0126] The specific resistance value is satisfied under the conditionsof use of the head provided for this study and can be developed to ageneral value by the following.

[0127] The frequency characteristic of a magnetic head depends on avalue fg(ρ, μ, t), even if the conditions of the magnetic pole arechanged, where ρ denotes the specific resistance value of magnetic polematerial, μ denotes the relative magnetic permeability of the materialand t denotes the thickness of a magnetic pole film. They have thefollowing relation.

fg=ρ/(μ×t2)  (1)

[0128] When the head conditions (magnetic pole conditions), which existfor 150 MHz driving, are substituted in the equation, the following isobtained.

fg′=50/(1000×2.82)≈0.0064  (2)

[0129] Consequently, the head conditions which exist for 150 MHzdriving, even if the condition of the magnetic film is changed, has tosatisfy the following.

ρ/(μ×t2)>0.0064  (3)

[0130] From the equation, it is understood that a material of ρ<50 μΩ·cmcan be applied when a magnetic pole of t2 is used.

[0131] This is satisfied under the condition that the thickness of theupper core and that of the lower core are equal to each other. When thethickness is different therebetween, however, it was confirmed that theequation is satisfied by using the thickness of the thicker core.Therefore, the equation can be applied to all magnetic heads having theconstruction of the invention.

[0132] A high frequency driving condition exceeding 150 MHz can be alsoobtained from the result shown in FIG. 20. That is, the value of ρ, atwhich a 65% or larger magnetic field with respect to the magnetostaticfield can be generated, is read and the value is substituted for theequation (2), thereby obtaining fg′. From the value fg′, a magnetic filmcondition (ρ, μ, t) satisfying the expression (3) can be obtained.

[0133] The state of driving at 150 MHz is realized by using materialhaving a specific resistance value of 50 μΩ·cm or higher, as long as thefilm thickness is not reduced. Although material having a specificresistance value of 50 μΩ·cm or higher has been developed, a magneticdisk apparatus using such material had not been developed, since thehigh frequency driving is developed together with an increase in thedensity of the apparatus.

[0134] That is, even if the density in the sliding direction(circumferential direction) becomes higher by improvement of the drivingfrequency, the data becomes serial and the access time increases (a reelmemory state), so that the random access performance as a feature of themagnetic disk deteriorates. In order to increase the density,consequently, it is necessary to increase the density not only in thesliding direction, but also in the track width direction by narrowingthe magnetic pole width.

[0135] A film having a high specific resistance, which can be formed byelectrolytic plating, has a high magnetostriction constant, as well as adrawback in that a crack easily occurs in a mask member, when a finepattern is formed. A multilayer film, in which an amorphous or oxidefilm or the like having an even higher specific resistance issandwiched, has a drawback in that a pattern cannot be formed byelectrolytic plating. There is accordingly a drawback in that a narrowmagnetic pole width cannot be realized. Consequently, a high frequencyand a high density cannot be obtained at the same time. Thus, a magnetichead, which is made of a material having a high electric resistance andwhich is driven at 150 MHz, and a magnetic disk apparatus using suchmagnetic head, could not have been realized.

[0136] In a fundamental magnetic head construction according to theinvention, by applying conditions satisfying the aforesaid formula (3)to the material and construction of the first and fourth magnetic films,a magnetic head driven at a frequency of 150 MHz or higher and amagnetic disk apparatus using the same magnetic head can be realized forthe first time. Such knowledge had never been disclosed conventionallyand is made clear for the first time from the results as shown in FIGS.19 and 20.

[0137] The result as shown in FIG. 19 is not influenced by the value ofthe specific resistance of the third magnetic film. It is a phenomenonlimited to a case where the volume of the third magnetic film describedin the embodiment is smaller than that of the first and fourth magneticfilms.

[0138]FIG. 23 shows the frequency characteristic, as in FIG. 19, inwhich the ratio of the volume of the third magnetic film and that of thefirst and fourth magnetic film patterns is used as a parameter. It isunderstood from this diagram that the more the volume ratio approachesthe more the frequency characteristic deteriorates (volume ratio 1simply means a state where patterns having the same thickness areoverlapped). The results are summarized as shown in FIG. 24 (it is shownin the same manner as in FIG. 20). It is understood from FIG. 24 thatthe more the volume ratio is reduced, the more the upper limit of thefrequency, at which the generated magnetic field becomes 65% or more ofthe magnetostatic field, is improved. However, the upper limit tends tobe saturated. It is also understood that the existence of the thirdmagnetic film can be almost ignored, if the volume of the third magneticfilm is set at 10⁻⁴ or smaller of the volume of the first and fourthmagnetic films. The volume of the third magnetic film is consequentlyspecified within this range in accordance with the invention.

[0139] As the third magnetic film, since a strong magnetic field forwriting has to be generated, other material conditions are required.FIG. 22 shows the relation between the saturable magnetic flux densityBs of the third magnetic film (it is assumed here that Bs of the secondmagnetic film is set to be the same) and the intensity of the generatedmagnetic field. The result of changing the Bs of the first and fourthmagnetic films as a parameter is shown. It is understood from the resultthat the more the Bs of the third magnetic film is increased, the moreintensive the generated magnetic field becomes. It is known thatgenerally speaking, a medium having high coercive force is suitable forhigh density recording. It is also known that the higher the coerciveforce of the medium is, the more intensive will be the magnetic fieldnecessary for writing. From the above, the necessity of selectingmaterial having a high Bs for the third magnetic film can be understood.

[0140] Even when the Bs of the third magnetic film was thoughtlesslyincreased, a writing of high resolution was not realized. It was foundthat this was because of a magnetizing gradient deterioration. FIG. 22also shows the result of the magnetizing gradients obtained. It isunderstood from the graph that when the magnetic field gradient is high(0.9 or higher in the normalized value), the range of Bs, in whichrecording could be performed with a high resolution, was as follows(experimental result: the range, in which the overwrite characteristicof 30 dB was obtained): when the value of Bs of the first and fourthmagnetic films is 1 T, that of the third magnetic film lies in the rangefrom 1 T to 1.7 T; and when the value of Bs of the first and fourthmagnetic films is 1.3 T, that of the third magnetic film lies in therange from 1.2 T to 2.3 T.

[0141] When the magnetic path of a magnetic head is considered, theaforesaid range can be described in a general relational expression. Inthe cross section of the magnetic head as shown in FIG. 21, the magneticflux flows from the first magnetic film 25 to the second magnetic film32, and from the third magnetic film 33 to the fourth magnetic film 27.The amount per unit length in the track width direction of the magneticflux flowing in each magnetic path can be approximately obtained fromthe product of the thickness t of the magnetic path (magnetic polethickness) and as. When Bs and t of the first and fourth magnetic filmsare equal to each other, respectively, a magnetic flux proportional toBs1×t flows in both films. It is understood that the whole of thismagnetic flux flows in the second and third magnetic films, when theproduct of the length Dg shown in FIG. 21 and Bs2 is equal (Dg is thelength of the overlap of the first and second magnetic films or thelength of the overlap of the fourth and third magnetic films).

[0142] Since the third magnetic film is positioned on the outflow endside with respect to the second magnetic film, the magnetic field fromthe third magnetic film exerts the most influence on the recordingstate. The conditions of the third magnetic film will be consequentlydescribed hereinbelow.

[0143] In the embodiment, since it is fixed as Dg=2 μm and t=2.8 μm,when Bs1 of the first and fourth magnetic films is set at 1 T, therelation is satisfied by setting Bs2 of the third magnetic film at about1.4 T. As this condition is far from the one stated above, the magneticflux in the third magnetic film becomes insufficient, or excessive(saturation of the magnetic pole). Therefore, the magnetic fielddistribution deteriorates.

[0144] The range for obtaining a preferable magnetic field distributioncan be consequently described by using the values of Bs1, t, Dg and Bs2.When Bx1×t and Dg×Bs2 are calculated with respect to the range, in whichthe preferable magnetic field distribution can be obtained, the resultsare as follows:

[0145] in case of Bs1×t=2.8,

[0146] Dg×Bs2=2 to 3.4, and

[0147] in case of Bs1×t=3.64,

[0148] Dg×Bs2=2.4 to 4.6

[0149] When the range is described by using Bs1×t/Dg×Bs2, the range, inwhich a preferable magnetic field gradient can be obtained, is asfollows:

0.8<Bs1×t/Dg×Bs2<1.5  (4)

[0150] Recording with a high resolution can be realized by using themagnetic head construction of the invention and by satisfying the abovementioned condition.

[0151] The specific resistance of the first and fourth magnetic films isgenerally higher than that of the third magnetic film. Further, thevolume of the first magnetic film becomes larger than that of the thirdmagnetic film. Moreover, it is preferable that the construction of amagnetic pole satisfies the formula (4).

[0152] Another feature of the magnetic head of the invention will bedescribed, hereinbelow. FIGS. 18A to 18C schematically show examples ofthe relation between the fourth magnetic film 127 and other magneticfilms 125, 132 and 133. According to the example of FIG. 18A, the shapeof the fourth magnetic film 127 is like a house and coincides with theshape of the upper core of the conventional magnetic head. In thisshape, it is obvious that the area of the second magnetic film 132 andthe third magnetic film 133, exposed to the cross section of themagnetic gap, is narrower than that of the fourth magnetic film 127which is similarly exposed.

[0153] With such a structure, when a general medium is used, apreferable recording operation could be realized. It was understood thatthe structure is not suitable for a medium having an especially smallcoercive force. The reason is that the recording operation is executedby the magnetic field from regions 151 shown in the diagram (the writingoperation occurs by a very weak magnetic field leaked from the fourthmagnetic film 127 to the first magnetic film 125). As obviouslyunderstood from the examples of FIG. 18A, since the fourth magnetic film127 is wide (when it is seen from the cross section close to the mediumface), when the writing operation occurs, neighboring information iseliminated.

[0154] In accordance with the invention, as shown in FIG. 18B, the shapeof the fourth magnetic film 127 is consequently changed. Specifically,by making the ends close to the sliding surface have a curvature, theedges (angles) of the fourth magnetic film are prevented from appearingto the sliding face. A magnetic charge is apt to be concentrated on anedge, so that a leaked magnetic field from an edge inevitably will bestrong. By allowing the fourth magnetic film 127 to have a curvature asshown in the drawing, there is no concentration of the magnetic charge,with the result that an erroneous writing operation to the adjacenttrack, which is a problem in the above technique of FIG. 18A, does notoccur. In this case, the area of the fourth magnetic film 127 can bemade narrower than that of the second and third magnetic films, as seenfrom the sliding surface. By spacing the end of the fourth magnetic film127 from the sliding surface by an amount a, as shown in FIG. 18C, asimilar effect could be obtained even in the shape where the magneticfilm is not exposed to the sliding surface. It can be understood thatthe writing operation does not occur because the edge of the fourthmagnetic film is spaced from the medium face.

[0155] Although only the fourth magnetic film is embodied, it goeswithout saying that the first magnetic film can be also changed.However, the first magnetic film does not have to be particularlychanged. By changing the shape of the fourth magnetic film pattern, thedistance between facing magnetic poles (the distance between themagnetic poles in the regions 151 as shown in FIG. 18A can be widened,and so the leaked magnetic field does not exert any influence on theadjacent track from the above mentioned effect. In the following, amethod of fabricating a magnetic head (of the invention), in which anon-magnetic film having a single structure is provided between thesecond and third magnetic films, will be described with reference toFIGS. 17A to 17F. The processes will be sequentially described.

[0156]FIG. 17A shows a state in which frame pattern 171-1 fordetermining the shapes of the second and third magnetic films is formedafter the first magnetic layer 125 serving as the lower core isdeposited on the substrate. In this case, in order to simultaneouslyform a back contact pattern, frame 171-2 is formed. The frame patterns171-1 and 171-2 are made of a high polymer resin such as a resist orsilicon oxide or the like. The cross section of the frame pattern isvertical and has to be minute. For these reasons, a thin film resistpattern is first formed and is transferred to a film of inorganicmatter, and after that, the thin film pattern is used as a mask and thehigh polymer resin or the like of an underlayer is etched. For thisetching, anisotropic etching using oxygen, fluorine gas, or the like issuitable (a multilayer process used for fabricating a semiconductordevice is suitable).

[0157] After that, as shown in FIG. 17B, the second magnetic film, thenon-magnetic conductive film (specifically, Cu, Ta, or the like) forforming the recording gap, and the third magnetic film are deposited.The films are formed by electrolytic plating (or electroless plating).After that, resist patterns 172-1 and 172-2 are overlayed on regions atleast covering the frames 171-1 and 171-2.

[0158] After forming those patterns, the area, which is rot covered bythe resist patterns, is removed by a wet method. After that, as shown inFIG. 17C, by removing the frames and resist patterns, the secondmagnetic film 132, the magnetic gap 110, the third magnetic film 133,the magnetic path materials 141, 142, and the magnetic gap 140 can beformed.

[0159] The two-dimensional shape of the second magnetic film and that ofthe third magnetic film are the same. Since the formation of the patterncan be completed in a single operation, it is efficient.

[0160] After that, as shown in FIG. 17D, the insulating film 131 in theform of an alumina film or the like is applied so as to cover the wholeregion of the first magnetic film. The surface of each of the thirdmagnetic film 133 and the magnetic path material 142 (back contact) isthen exposed. For this process, a method of mechanically polishing thesurface or a planarization process, which is used for fabricating thesemiconductor device or the like, is used. The planarization process isperformed by thickly applying a resin to smoothen steps, performing dryetching to a desired thickness while keeping the smooth face, andexposing a part of a projection on the smooth face by keeping etchingspeed of the resin and that of the projection at 1:1. Since theinsulating layer can be selectively removed by a single process in anycase, the productivity is excellent and the manufacturing costs of theapparatus can be reduced.

[0161] After forming the coil 126 as shown in FIG. 17E, the insulatinglayer 138 is formed. The insulating layer 138 is tapered toward thethird magnetic film. Opening 134 is formed in a back contact part (forexposing the surface of the magnetic path material 142) and a contactingpart of the coil 126 and the electrode.

[0162] After that, the fourth magnetic film 127 is formed by an ionmilling method or a lift-off method. By connecting the electrode to thecontact hole 134, the fabrication of a main part (only the writing part)of the magnetic head is finished.

[0163] By the above mentioned processes, the magnetic pole structureshown in FIG. 16A and FIG. 16B can be formed. The magnetic head isformed on a wafer obtained by mechanically processing a sintered body ofalumina and titanium carbide, thereby fabricating the magnetic headslider.

[0164] The structure of FIG. 17C also can be formed by forming the thirdmagnetic film pattern by electrolytic plating and etching by using thepattern as a mask. For the etching, an ion milling method is suitable.In order to form the magnetic gap and the second magnetic film by thismethod, it is obviously understood that the insulating film(constructing the recording gap) made of alumina or the like and themagnetic film have to be preliminarily deposited under the thirdmagnetic film. This causes no problem, even if the magnetic film is madeof the same material as that of the first magnetic film positionedbelow, as long as the third magnetic film is positioned on the outflowend side with respect to the second magnetic film.

[0165] The magnetic head of the invention formed by the above processesis attached to suspension member 117 as shown in FIG. 12A. The rotaryactuator 53 is used to position the magnetic head 40 attached to the endof the suspension member 117 at an arbitrary position above therecording medium 51. The existence of the arm 114 used for connectingthe rotary actuator 53 and the suspension member 117 is unnecessary in arecording apparatus of 2.5 inches or smaller.

[0166] The magnetic recording apparatus having a magnetic head with theabove construction is extremely reliable, since the hard alumina film orthe like is exposed to the sliding surface side. The track width(magnetic pole width) of the writing part forming the magnetic head isdetermined by the width of the third magnetic film. Since the patterncan be formed by electrolytic plating, a magnetic recording apparatuscorresponding to a narrow track of 1 μm or narrower can be easilymanufactured.

[0167] By using material having a high specific resistance for the firstand fourth magnetic films, a magnetic head driven at the frequency of150 MHz or higher can be realized. From the above effects, a high-speedand high-density (10 Gb/in² or higher) magnetic recording apparatus,which is conventionally considered to be impossible to realize, can berealized. This is the result of the optimization of the insulating filmstructure, the optimization of the magnetic film, and the like. Themagnetic recording apparatus (magnetic head) of the invention havingsuch features can be manufactured at low cost without requiring anycomplicated manufacturing means.

1. A method of forming a thin film magnetic head, comprising the stepsof: forming a first magnetic layer; forming a second magnetic layer as amagnetic flux passage in combination with the first magnetic layer; andforming a laminate structure body between the first magnetic layer andthe second magnetic layer; wherein the step of forming the laminatestructure body includes forming a third magnetic layer, a fourthmagnetic layer and a non-magnetic conductive layer between the thirdmagnetic layer and the fourth magnetic layer, projecting the laminatestructure body more toward an air bearing surface than a projection ofthe first magnetic layer and the second magnetic layer toward the airbearing surface, and providing the laminate structure body with a widthwhich is smaller than a width of the first magnetic layer and the secondmagnetic layer; and wherein the forming of each of the third magneticlayer and the fourth magnetic layer includes utilizing a plated magneticfilm having a saturable magnetic flux density of at least 1.5 tesla, andthe forming of the second magnetic layer includes utilizing plating orsputtering and providing a width wider than the frame width of theplated magnetic film and a specific resistance of at least 50 μΩ·cmunder a condition that the thin film magnetic head performs apredetermined high density recording at a predetermined high drivingfrequency.
 2. The method according to claim 1 , wherein the thirdmagnetic layer and the fourth magnetic layer are formed to have the sametrack width, each of the first magnetic layer and the second magneticlayer is formed to have a width wider than said track width of the thirdand fourth magnetic layers, and the second magnetic layer is formed as amultilayered magnetic film.
 3. The method according to claim 2 , whereinthe thin film magnetic head is a recording head further comprising thestep of forming a recording/reproduction separation type magnetic headin which the recording head is utilized for writing information and areproduction head is integrally formed therewith which is utilized forreading information.
 4. The method according to claim 3 , wherein thereproduction head is formed so as to include a ferromagnetic layerhaving magnetic resistive effect and an antiferromagnetic layer forallowing the ferromagnetic layer to show one-way anisotropy, and theantiferromagnetic layer is made of an Cr—Mn alloy.
 5. The methodaccording to claim 1 , wherein when a saturable magnetic flux density ofthe second magnetic layer is denoted by Bs1 (Y), a film thickness byt(μm), a saturable magnetic flux density of the fourth magnetic layer byBs2 (T) and an overlapped length in a floating direction of the secondand fourth magnetic layers by Dg (μm), the following relation issatisfied: 0.8<Bs1t×/Bs2×Dg<1.5.
 6. The method according to claim 5 ,wherein the third magnetic layer is made of the same material as that ofsaid first magnetic layer.
 7. A method of forming thin film magnetichead, comprising the steps of: forming a first magnetic layer; forming asecond magnetic layer; and forming a laminate structure body between thefirst magnetic layer and the second magnetic layer with a narrower widththan a width of the first magnetic layer and the second magnetic layer;wherein the step of forming the laminate structure body includes forminga third magnetic layer, a fourth magnetic layer and a non-magneticconductive layer between the third magnetic layer and the fourthmagnetic layer, magnetically coupling the first magnetic layer andsecond magnetic layer at one end thereof with the laminate structurebody which is projected more toward an air bearing surface than aprojection of the first magnetic layer and the second magnetic layertoward the air bearing surface, and magnetically coupling the firstmagnetic layer and the second magnetic layer to each other at an otherend thereof; and wherein the forming of each of the third magnetic layerand the fourth magnetic layer includes utilizing a plated magnetic filmhaving a saturable magnetic flux density of at least 1.5 tesla, and theforming of the second magnetic layer includes utilizing plating orsputtering and providing a width wider than a frame width of the platedmagnetic film and a specific resistance of at least 50 μΩ·cm under acondition that the thin film magnetic head performs a predetermined highdensity recording at a predetermined high driving frequency.
 8. Themethod according to claim 7 , wherein the third magnetic layer and thefourth magnetic layer are formed to have the same track width, each ofthe first magnetic layer and the second magnetic layer is formed to havea width wider than the track width of the third and fourth magneticlayers, and the second magnetic layer is formed as a multilayeredmagnetic film.
 9. A method according to claim 8 , wherein the thin filmmagnetic head is a recording head, and further comprising the step offorming a recording/reproduction separation type magnetic head in whichthe recording head is utilized for writing information and areproduction head is integrally formed therewith which is utilized forreading information.
 10. The method according to claim 9 , wherein thereproduction head is formed so as to include a ferromagnetic layerhaving magnetic resistive effect and an antiferromagnetic layer forallowing the ferromagnetic layer to show one-way anisotropy, and theantiferromagnetic layer is made of an Cr—Mn alloy.
 11. The methodaccording to claim 7 , wherein when a saturable magnetic flux density ofthe second magnetic layer is denoted by Bs1 (Y), a film thickness byt(μm), a saturable magnetic flux density of the fourth magnetic layer byBs2 (T) and an overlapped length in the floating direction of the secondand fourth magnetic layers by Dg (μm), the following relation issatisfied: 0.8<Bs1×t/Bs2×Dg<1.5.
 12. The method according to claim 11 ,wherein the third magnetic layer is made of the same material as that ofthe first magnetic layer.